1. Field of the Invention
The present invention relates to planar electrochromic dimmers used in dimming devices such as sun roofs for cars, and others.
2. Description of the Related Art
In sun roofs for cars, in order to set the visible ray transmittivity to about 30%, a method where a butyral film used in the plate glass itself and in the laminated glass is colored, and a method which involves mesh printing are being used. Also, glass dimmers that make use of electrochromic elements to change the coloring conditions are also being proposed.
In the methods mentioned above, in which the visible ray transmittivity is decreased by means of the usual coloring effect of electrochromic elements, the electrochromic element generates heat due to the absorption of the rays, resulting in the deterioration of its thermal insulating effect.
The visible ray transmittivity of ordinary electrochromic elements is about 60% in the discoloring conditions and about 10% in the coloring conditions. However, the 10% visible ray transmittivity is not enough in insulate light. Also, it is possible to get lower transmittivity by impressing high voltage upon the electrochromic elements, but such electrochromic elements deteriorate quickly and have a problem with endurance. When the glass dimmers are used to insulate light for sun roofs for cars, desirable change of the transmittivity of the electrochromic elements is about from 30% to 5%. However, when the adjustment is done by the electrochromic elements only, it is necessary to control electrochromic elements in the constant coloring conditions. Especially, in the case of adjusting the visible ray transmittivity at 5%, the electrochromic elements are loaded and cause problem in endurance.